Answer:
Your strategy here will be to use the molar mass of potassium bromide,
KBr
, as a conversion factor to help you find the mass of three moles of this compound.
So, a compound's molar mass essentially tells you the mass of one mole of said compound. Now, let's assume that you only have a periodic table to work with here.
Potassium bromide is an ionic compound that is made up of potassium cations,
K
+
, and bromide anions,
Br
−
. Essentially, one formula unit of potassium bromide contains a potassium atom and a bromine atom.
Use the periodic table to find the molar masses of these two elements. You will find
For K:
M
M
=
39.0963 g mol
−
1
For Br:
M
M
=
79.904 g mol
−
1
To get the molar mass of one formula unit of potassium bromide, add the molar masses of the two elements
M
M KBr
=
39.0963 g mol
−
1
+
79.904 g mol
−
1
≈
119 g mol
−
So, if one mole of potassium bromide has a mas of
119 g
m it follows that three moles will have a mass of
3
moles KBr
⋅
molar mass of KBr
119 g
1
mole KBr
=
357 g
You should round this off to one sig fig, since that is how many sig figs you have for the number of moles of potassium bromide, but I'll leave it rounded to two sig figs
mass of 3 moles of KBr
=
∣
∣
∣
∣
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
a
a
360 g
a
a
∣
∣
−−−−−−−−−
Explanation:
<em>a</em><em>n</em><em>s</em><em>w</em><em>e</em><em>r</em><em>:</em><em> </em><em>3</em><em>6</em><em>0</em><em> </em><em>g</em><em> </em>
953.6 g of iron (III) oxide (Fe₂O₃)
Explanation:
We have the following chemical reaction:
2 Fe₂O₃ (s) + 3 C (s) → 4 Fe (s) + 3 CO₂ (g)
We calculate the number of moles of CO₂ by using the following formula:
pressure × volume = number of moles × gas constant × temperature
number of moles = (pressure × volume) / (gas constant × temperature)
number of moles of CO₂ = (2.1 × 100) / (0.082 × 300)
number of moles of CO₂ = 8.54 moles
Taking in account the chemical reaction we devise the following reasoning:
if 2 mole of Fe₂O₃ produces 3 mole of CO₂
then X moles of Fe₂O₃ produces 8.54 mole of CO₂
X = (2 × 8.54) / 3 = 5.69 moles of Fe₂O₃
number of moles = mass / molar weight
mass = number of moles × molar weight
mass of Fe₂O₃ = 5.69 × 160 = 953.6 g
Learn more about:
number of moles
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Electron affinity is the energy released when an electron is accepted by a neutral atom forming a negative ion. Chlorine has the higher electron affinity because it readily accepts an electron to become more stable. On the other hand, sodium have to give up an electron to complete its valence shell.
Answer:
The ones with 8 protons
Explanation:
Since there are two of them with 8 protons, we can assume they are the same element. The first 8 proton element has 10 neutrons while the second has 11. This makes them isotopes of one another
